Reduction of saprolite nickel ore using methane-argon gas mixture with laboratory-scale simulated rotary kiln-electric furnace (RKEF) technology

Saprolite nickel ore is typically processed using a pyrometallurgical route called Rotary Kiln-Electric Furnace (RKEF), which contributes to about 75 % of nickel production from laterite nickel ores. In RKEF technology, coal plays multiple roles as a reductant, fuel, and electricity source. Methane is a viable option as reductant and fuel for reducing CO₂ emissions in the nickel industry, particularly as a stopgap measure until hydrogen production can be scaled up. However, there has been limited research on using methane as a reductant in nickel production. This study aims to produce ferronickel from saprolite nickel ore through a laboratory-scale RKEF using methane gas. Initially, FactSage 8.2 was used to investigate the thermodynamics of the process. A series of laboratory experiments were carried out in two stages to simulate the RKEF process. It involved varying the reduction temperature (500–900 °C), reduction time (15–120 min), and gas composition (25 and 75 vol% CH₄/Ar) before each calcine was melted at 1550 °C for 2 h. The average composition of metals obtained was 71.3 % Fe and 14.3 % Ni. The results showed that methane can be used to produce ferronickel with a similar composition as commercial ferronickel.